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Due to the large sizes of landmasses and the fact that most humans
have never viewed the earth from above a few kilometres (from
mountains) until the 20th century, people have historically been
unable to judge the earth's sphericity and curvature. This is
despite the large distances people have travelled.

The Hebrew Bible carried forward the ancient Middle Eastern
cosmology, revealed partly in the Enuma
Elish, which described a flat earth with a solid roof,
surrounded by water above and below.

Isaiah 40:22

There is an occasional opinion offered that an early statement of a
spherical earth occurs in the 8th century BC, in Isaiah 40:22
"It is he that sitteth upon the circle of the earth...".
There are problems with this claim, the most obvious being that the
text says "circle", not "sphere". The Hebrew word translated as
"circle" is generally recognized as referring to a plane figure,
perhaps the horizon, or possibly the vault of the heavens. A
secondary issue is that this text is part of Deutero-Isaiah, often ascribed to the 6th
century BC (and thus roughly contemporaneous with
Pythagoras).

History of Western ideas

By classical times the idea that
Earth was spherical began to take hold in Ancient Greece. Pythagoras in the 6th century BC, apparently on
aesthetic grounds, held that all the celestial bodies were spherical.
However, most Presocratic Pythagoreans
considered the world to be flat. According to Aristotle, pre-Socratic philosophers, including
Leucippus (c. 440 BC) and Democritus (c. 460–370 BC) believed in a flat
earth. Anaximander believed the Earth to
be a short cylinder with a flat, circular top which remained stable
because it is the same distance from all things. It has been
suggested that seafarers probably provided the first observational
evidence that the Earth was not flat.

Around 330 BC, Aristotle provided
observational evidence for the spherical Earth, noting that
travelers going south see southern constellations rise higher above the horizon.
He argued that this was only possible if their horizon was at an
angle to northerners' horizon and that the Earth's surface
therefore could not be flat. He also noted that the border of the
shadow of Earth on the Moon during the partial
phase of a lunar eclipse is always
circular, no matter how high the Moon is over the horizon. Only a
sphere casts a circular shadow in every direction, whereas a
circular disk casts an elliptical shadow in
all directions apart from directly above and directly below.
Writing around 10 BC, the Greek geographer Strabo cited various phenomena observed at sea as
suggesting that the Earth was spherical.

When a ship is at the horizon, its lower part is invisible due
to the sphericity of the Earth.

This phenomenon provided evidence of the Earth's surface being
round instead of flat.

He observed that elevated lights or areas of land were visible to
sailors at greater distances than those which were less elevated,
and stated that the curvature of the sea was obviously responsible
for this. He also remarked that observers can see further when
their eyes are elevated, and cited a line from the Odyssey as indicating that the poet Homer was already aware of this as early as the 7th or
8th century BC.

The Earth's circumference was first
determined around 240 BC by Eratosthenes. Eratosthenes knew that in Syene, in Egypt, the Sun was
directly overhead at the summer solstice,
while he estimated that the angle formed by a shadow cast by the
Sun at Alexandria was 1/50th of a circle. He estimated the
distance from Syene to Alexandria as 5,000 stade, and estimated the Earth's
circumference was 250,000 stades and a degree was 700 stades
(implying a circumference of 252,000 stades). Eratosthenes used
rough estimates and round numbers, but depending on the length of
the stadion, his result is within a
margin of between 2% and 20% of the actual meridionalcircumference, . Note that Eratosthenes could only measure the
circumference of the Earth by assuming that the distance to the Sun is so great that the
rays of sunlight are essentially parallel.

Lucretius (1st. c. BC) opposed the concept
of a spherical Earth, because he considered the idea of antipodes absurd. But by the 1st century AD, Pliny the Elder was in
a position to claim that everyone agrees on the spherical shape of
Earth, although there continued to be disputes regarding the nature
of the antipodes, and how it is possible to keep the ocean in a curved shape. Pliny also considers the
possibility of an imperfect sphere, "shaped like a pinecone".

In the second century the Alexandrian astronomer Ptolemy advanced many arguments for the sphericity
of the Earth. Among them was the observation that when sailing
towards mountains, they seem to rise from
the sea, indicating that they were hidden by the curved surface of
the sea. He also gives separate arguments that the Earth is curved
north-south and that it is curved east-west. Ptolemy derived his maps from a curved globe and
developed the system of latitude, longitude, and climes. His
writings remained the basis of European astronomy throughout the Middle Ages, although Late Antiquity and the Early Middle Ages (ca. 3rd to 7th
centuries) saw occasional arguments in favor of a flat Earth.

The Jerusalem Talmud says that
Alexander of Macedon (Alexander the
Great) was lifted by birds to the point that he saw the
curvature of the earth. This story is mentioned as well by the
Tosafos commentary on the Babylonian
Talmud. This is used to explain why a statue of a person
holding a sphere in his hand is assumed to be an idol. The sphere
being held in its hand symbolizing the idol's purported dominion
over the world whose shape is a sphere.

In late
antiquity such widely read encyclopedists as Macrobius (4th c.) and Martianus Capella (5th c.) discussed the
circumference of the sphere of the Earth, its central position in
the universe, the difference of the seasons
in northern and southern hemispheres, and many other geographical details. In his
commentary on Cicero'sDream of Scipio, Macrobius described
the Earth as a globe of insignificant size in comparison to the
remainder of the cosmos.

Early Christian Church

From Late Antiquity, and from the
beginnings of Christian theology,
knowledge of the sphericity of the Earth had become widespread.
There was some debate concerning the possibility of the inhabitants
of the antipodes: people imagined as separated by an impassable
torrid clime were difficult to reconcile with
the Christian view of a unified human race descended from one couple and redeemed by a single
Christ.

Saint Augustine (354–430) argued
against assuming people inhabited the antipodes:

But as to the fable that there are Antipodes, that is
to say, men on the opposite side of the earth, where the sun rises
when it sets to us, men who walk with their feet opposite ours,
that is on no ground credible.

And, indeed, it is not affirmed that this has been
learned by historical knowledge, but by scientific conjecture, on
the ground that the earth is suspended within the concavity of the
sky, and that it has as much room on the one side of it as on the
other: hence they say that the part which is beneath must also be
inhabited.

But they do not remark that, although it be supposed or
scientifically demonstrated that the world is of a round and
spherical form, yet it does not follow that the other side of the
earth is bare of water; nor even, though it be bare, does it
immediately follow that it is peopled.

Since these people would have to be descended from Adam, they would have had to travel to the
other side of the Earth at some point; Augustine continues:

It is too absurd to say, that some men might have taken
ship and traversed the whole wide ocean, and crossed from this side
of the world to the other, and that thus even the inhabitants of
that distant region are descended from that one first
man.

Scholars of Augustine's work have traditionally understood him to
have shared the common view of his educated contemporaries that the
earth is spherical, in line with the quotation above, and with
Augustine's famous endorsement of science in De Genesi ad
litteram. That tradition has, however, recently been
challenged by Leo Ferrari, who concluded that many of Augustine's
passing references to the physical universe imply a belief in an
essentially flat earth "at the bottom of the universe".

Some authors and artists less prominent in the Church's history
directly opposed the round Earth. After his conversion to
Christianity, Lactantius (245–325) became
a trenchant critic of all pagan philosophy. In Book III of The
Divine Institutes he ridicules the notion that there could be
inhabitants of the antipodes "whose footsteps are higher than their
heads". After presenting some arguments which he claims advocates
for a spherical heaven and earth had advanced to support their
views, he writes:

Cosmas Indicopleustes' world picture -
flat earth in a Tabernacle.

But if you inquire from those who defend these
marvellous fictions, why all things do not fall into that lower
part of the heaven, they reply that such is the nature of things,
that heavy bodies are borne to the middle, and that they are all
joined together towards the middle, as we see spokes in a wheel;
but that the bodies which are light, as mist, smoke, and fire, are
borne away from the middle, so as to seek the heaven. I am at a
loss what to say respecting those who, when they have once erred,
consistently persevere in their folly, and defend one vain thing by
another;

Diodorus of Tarsus (d. 394) may
have argued for a flat Earth based on scriptures; however,
Diodorus' opinion on the matter is known to us only by a criticism
of it by Photius.
Severian, Bishop of
Gabala (d. 408), wrote: "The earth is flat and the sun does not
pass under it in the night, but travels through the northern parts
as if hidden by a wall". The Egyptian monk Cosmas Indicopleustes (547) in his
Topographia Christiana, where
the Covenant Ark was meant to represent the whole universe, argued
on theological grounds that the Earth was flat, a parallelogram enclosed by four oceans.

At least one early Christian writer, Basil of Caesarea (329–379), believed the
matter to be theologically irrelevant.

With the end of Roman civilization, Western Europe entered the Middle Ages with great difficulties that
affected the continent's intellectual production. Most scientific
treatises of classical antiquity
(in Greek) were unavailable, leaving
only simplified summaries and compilations. Still, the dominant
textbooks of the Early Middle Ages supported the sphericity of the
Earth. For example: many early medieval manuscripts of Macrobius
include maps of the Earth, including the antipodes, zonal maps showing the Ptolemaic
climates derived from the concept of a spherical Earth and a
diagram showing the Earth (labeled as globus terrae, the
sphere of the Earth) at the center of the hierarchically ordered
planetary spheres. Further examples of such medieval diagrams can
be found in medieval manuscripts of the Dream of Scipio. In the Carolingian era, scholars discussed
Macrobius's view of the antipodes. One of them, the Irish monk
Dungal, asserted that the tropical gap
between our habitable region and the other habitable region to the
south was smaller than Macrobius had believed.

Boethius (c. 480 – 524), who also wrote
a theological treatise On the Trinity, repeated the
Macrobian model of the Earth as an insignificant point in the
center of a spherical cosmos in his influential, and widely
translated, Consolation of
Philosophy.

Bishop Isidore of Seville
(560 – 636) taught in his widely read encyclopedia, the
Etymologies, that the Earth was
round. His meaning was ambiguous and some writers think he referred
to a disc-shaped Earth; his other writings make it clear, however,
that he considered the Earth to be globular. He also admitted the
possibility of people dwelling at the antipodes, considering them
as legendary and noting that there was no evidence for their
existence. Isidore's disc-shaped analogy continued to be used
through the Middle Ages by authors clearly favouring a spherical
Earth, e.g. the 9th century bishop Rabanus Maurus who compared the habitable
part of the northern hemisphere (Aristotle's northern temperate clime) with a
wheel, imagined as a slice of the whole sphere.

The monk Bede (c.672 – 735) wrote in his
influential treatise on computus, The
Reckoning of Time, that the Earth was round, explaining the
unequal length of daylight from "the roundness of the Earth, for
not without reason is it called 'the orb of the world' on the pages
of Holy Scripture and of ordinary literature. It is, in fact, set
like a sphere in the middle of the whole universe." (De temporum ratione, 32). The large
number of surviving manuscripts of The Reckoning of Time,
copied to meet the Carolingian
requirement that all priests should study the computus, indicates
that many, if not most, priests were exposed to the idea of the
sphericity of the Earth. Ælfric
of Eynsham paraphrased Bede into Old
English, saying "Now the Earth's roundness and the Sun's orbit
constitute the obstacle to the day's being equally long in every
land."

Bishop Vergilius of
Salzburg (c.700 – 784) is sometimes cited as having been
persecuted for teaching "a perverse and sinful doctrine ...
against God and his own soul" regarding the sphericity of the
earth. Pope Zachary decided that "if it
shall be clearly established that he professes belief in another
world and other people existing beneath the earth, or in another
sun and moon there, thou art to hold a council, and deprive him of
his sacerdotal rank, and expel him from the church." The issue
involved was not the sphericity of the Earth itself, but whether
people living in the antipodes were not descended from Adam and
hence were not in need of redemption. Vergilius succeeded in
freeing himself from that charge; he later became a bishop and was canonised in
the thirteenth century.

A non-literary but graphic indication that people in the Middle
Ages believed that the Earth was a sphere, is the use of the
orb (globus
cruciger) in the regalia of many kingdoms and of the Holy Roman
Empire. It is attested from the time of the Christian late-Roman
emperor Theodosius II (423) throughout
the Middle Ages; the Reichsapfel was used in 1191 at the
coronation of emperor Henry
VI.

A recent study of medieval concepts of the sphericity of the Earth
noted that "since the eighth century, no cosmographer worthy of
note has called into question the sphericity of the Earth."
However, the work of these intellectuals may not have had
significant influence on public opinion, and it is difficult to
tell what the wider population may have thought of the shape of the
Earth, if they considered the question at all.

Some
historians consider that the early advocates who projected flat
Earth upon Christians of the Middle Ages were highly influential
(19th century view typified by diplomat and author Andrew Dickson
White); other historians strongly criticized White's work
of projection as anti-historical (19th century view typified by
physician and author James Joseph
Walsh); current historians have determined White's and other
writings projecting flat Earth belief upon Christians as
inaccurate, cited centuries of theological writings, and suggested
the motivations for the promotion of such inaccuracies (late 20th
century view typified by Religious Studies Scholar Jeffrey Burton Russell).

Hermannus Contractus
(1013–1054) was among the earliest Christian scholars to estimate
the circumference of Earth with Eratosthenes' method. Thomas Aquinas (1225–1274), the most
important and widely taught theologian of the Middle Ages, believed
in a spherical Earth; and he even took for granted his readers also
knew the Earth is round. Lectures in the medieval universities commonly
advanced evidence in favor of the idea that the Earth was a sphere.
Also, "On the Sphere of the
World", the most influential astronomy textbook of the 13th century and
required reading by students in all Western European universities,
described the world as a sphere. Thomas Aquinas, in his Summa Theologica, wrote, "The physicist
proves the earth to be round by one means, the astronomer by
another: for the latter proves this by means of mathematics, e.g.
by the shapes of eclipses, or something of the sort; while the
former proves it by means of physics, e.g. by the movement of heavy
bodies towards the center, and so forth."

The shape of the Earth was not only discussed in scholarly works
written in Latin; it was also treated in works
written in vernacular languages or
dialects and intended for wider audiences. The Norwegian book
Konungs Skuggsjá, from around
1250, states clearly that the Earth is round - and that it is night
on the other side of the Earth when it is daytime in Norway. The
author also discusses the existence of antipodes - and he notes
that they (if they exist) will see the Sun in the north of the
middle of the day, and that they will have opposite seasons of the
people living in the Northern Hemisphere.

Reinhard Krüger, a professor for Romance literature at the
University of Stuttgart (Germany), has identified more than 100
medieval Latin and vernacular writers - 79 known by name - from the
late antiquity to the 15th century, all of whom were convinced that
the earth was spherical:

Portuguese exploration of Africa and
Asia, Columbus voyage to the Americas (1492)
and finally Ferdinand Magellan's
circumnavigation of the earth (1519-21) provided the final,
practical proofs for the global shape of the earth.

The common misconception that people before the age of exploration believed that Earth
was flat entered the popular imagination after Washington Irving's publication of The
Life and Voyages of Christopher Columbus in 1828. This belief
is even repeated in some widely read textbooks. Previous editions
of Thomas Bailey'sThe American Pageant stated that
"The superstitious sailors [of Columbus' crew] ... grew
increasingly mutinous...because they were fearful of sailing over
the edge of the world"; however, no such historical account is
known. Actually, sailors were probably among the first to know of
the curvature of Earth from everyday observations, for example
seeing how mountains vanish below the horizon on sailing far from
shore.

Irving
builds his story of the 1486 Salamanca meeting around the issue of the sphericity of the
Earth. He presents some of the arguments against the
sphericity (based on the impossibility that there be unredeemed or
unredeemable humans on the opposite side); however, he also admits
that other learned scholars of the day accepted the sphericity of
the Earth.

In reality, the issue in the 1490s was not the shape but the size
of the Earth, as well as the position of the east coast of Asia.
Historical estimates from Ptolemy onwards placed the coast of Asia about 180°
east of the Canary
Islands (the actual value is slightly short of
140⁰).Columbus adopted an earlier (and rejected)
distance of 225°, added 28° (based on Marco
Polo’s travels), and then placed Japan another 30°
further east.Starting from Cape St. Vincent in Portugal, Columbus made Eurasia
stretch 283° to the east, leaving the Atlantic as only 77° wide. Since he planned to leave
from the Canaries (9° further west), his trip to Japan would only
have to cover 68° of longitude.

Furthermore, Columbus mistakenly used a much shorter length for a
degree (he substituted the shorter 1480 m Italian “mile” for the
longer 2177 m Arabic “mile”), making his degree (and the
circumference of the Earth) about 75% of what it really was.
The
combined effect of these mistakes was that Columbus estimated the
distance to Japan to be only about 5,000 km (or only to the
eastern edge of the Caribbean) while the true figure is about
20,000 km. Portuguese and Spanish scholars may not have
known the exact distance to the east coast of Asia, but they
certainly knew that it was significantly farther than Columbus’
projection; and this was the basis of the criticism in Portugal and
Spain, whether academic or amongst mariners, of the proposed
voyage.

The disputed point, therefore, was not the shape of the Earth, nor
the idea that going west would eventually lead to Japan and China,
but the ability of European ships to sail that far across open
seas. The small ships of the day (Columbus’ three ships varied
between 20.5 and 23.5 m – or 67 to 77 feet – in length and carried
about 90 men) simply could not carry enough food and water to reach
Japan. In fact, the ships barely reached the eastern Caribbean
islands. Already the crews were mutinous, not because of some fear
of “sailing off the edge”, but because they were running out of
food and water with the possibility that there were no new supplies
within sailing distance. They were on the edge of starvation.

What saved Columbus, of course, was the unknown existence of the
Americas precisely at the point he thought he would reach Japan.
His ability to resupply with water and food from the Caribbean
islands allowed him to return safely to Europe. The academics were
right: it was not possible for a 1492 ship to sail west from Europe
across open oceans directly to Japan; mariners would have died long
before they reached their destination.

Ancient India

From
antiquity, a cosmological view prevailed in India that held
the Earth to consist of four continents grouped around the central
mountain Meru like the petals
of a flower; surrounding these continents was the outer
ocean. This view was elaborated in traditional Buddhist cosmology, which depicts the
world (in this case solar system/universe and not earth) as a vast,
flat oceanic disk (of the magnitude of a small planetary system),
bounded by mountains, in which the continents are set as small
islands. In the center of this disk is the immense Mount Sumeru, the linchpin of the world, around which the
stars, the Sun, and the Moon revolve; the change of day and night
is caused by the occultation of the Sun by this mountain. This
world (in this case solar system/universe and not earth) is only
one of an infinite number of similar worlds, which extend in all
directions.

The works of the classical Indian
astronomer and mathematician,
Aryabhata (476-550 AD), deal with the
sphericity of the Earth and the motion of the planets. The final
two parts of his Sanskrit magnum opus the
Aryabhatiya, which were named the
Kalakriya ("reckoning of time") and the Gola
("sphere"), state that the earth is spherical and that its
circumference is 4,967 yojanas, which in modern units is , which is
close to the current equatorial value of .
He also stated that the apparent rotation of the celestial objects
was due to the actual rotation of the earth, calculating the length
of the sidereal day to be 23 hours, 56
minutes and 4.1 seconds, which is also surprisingly accurate. It is
likely that Aryabhata's results influenced European astronomy,
because the 8th century Arabic version of the
Aryabhatiya was translated into Latin in the 13th century.

China and the Far East

Ancient belief

In ancient China, the prevailing
belief was that the earth was flat and square, while the heavens
were round, an assumption which remained virtually unquestioned
until the introduction of European astronomy in the 17th century.
The English sinologist Cullen emphasizes the point that there was
no concept of a round earth in ancient Chinese astronomy:

Chinese thought on the form of the earth remained
almost unchanged from early times until the first contacts with
modern science through the medium of Jesuit
missionaries in the seventeenth century.

While the heavens were variously described as being
like an umbrella covering the earth (the Kai Tian theory), or like
a sphere surrounding it (the Hun Tian theory), or as being without
substance while the heavenly bodies float freely (the Hsüan yeh
theory), the earth was at all times flat, although perhaps bulging
up slightly.

Counterexamples by the historian Joseph
Needham supposed to demonstrate dissenting voices from the
general consensus actually refer without exception to the earth's
being square, not to its being flat. This is also true of Zhang Heng's often quoted theory (78-139 AD) that
the universe was in the oval shape of a hen's egg, and the earth
itself was like the curved yolk within:

In a passage of Zhang Heng's cosmogony not translated
by Needham, Zhang himself says: "Heaven takes its body from the
Yang, so it is round and in motion.

Earth takes its body from the Yin, so it is flat and
quiescent".

The point of the egg analogy is simply to stress that
the earth is completely enclosed by heaven, rather than merely
covered from above as the Kai Tian describes.

Chinese astronomers, many of them brilliant men by any
standards, continued to think in flat-earth terms until the
seventeenth century; this surprising fact might be the
starting-point for a re-examination of the apparent facility with
which the idea of a spherical earth found acceptance in
fifth-century B.C.

Greece.

Likewise, the 13th century scholar Li Ye,
arguing that the movements of the round heaven would be hindered by
a square earth, did not advocate a spherical earth, but rather that
its edge should be rounded off so as to be spherical as well.

Western impact

As late as 1595, the first Jesuit missionary
to China, Matteo Ricci, recorded that
the Chinese say: "The earth is flat andsquare, and the sky is a
round canopy; they did not succeed in conceiving the possibility of
the antipodes". The universal belief in a flat earth is confirmed
by a contemporary Chinese encyclopedia from 1609 illustrating a
flat earth extending over the horizontal diametral plane of a
spherical heaven.

In the 17th century, the idea of a spherical earth spread in China
due to the influence of the Jesuits, who held high positions as
astronomers at the imperial court. The Ge Chi Cao treatise
of Xiong Ming-yu (1648) showed a printed picture of the earth as a
spherical globe, with the text stating that "the round earth
certainly has no square corners". The text also pointed out that
sailing ships could return to their port of origin after
circumnavigating the waters of the earth.

The influence of the map is distinctly Western, as traditional maps
of Chinese cartography held the graduation of the sphere at 365.25
degrees, while the Western graduation was of 360 degrees. Also of
interest to note is on one side of the world, there is seen
towering Chinese pagodas, while on
the opposite side (upside-down) there were European cathedrals. Western influence of geographical knowledge was used by Xiong to
enforce what he believed had already been argued by earlier Chinese
astronomers. However, the French sinologist Jean-Claude Martzloff
regards this as a retrospective interpretation:

European astronomy was so much judged worth
consideration that numerous Chinese authors developed the idea that
the Chinese of antiquity had anticipated most of the novelties
presented by the missionaries as European discoveries, for example,
the rotundity of the earth and the “heavenly spherical star carrier
model.” Making skillful use of philology, these authors cleverly
reinterpreted the greatest technical and literary works of Chinese
antiquity.

From this sprang a new science wholly dedicated to the
demonstration of the Chinese origin of astronomy and more generally
of all European science and technology.

Medieval Islamic world

Around
830 AD, Caliph al-Ma'mun commissioned a
group of astronomers to measure the distance from Tadmur (Palmyra) to al-Raqqah, in modern Syria. They found the cities to
be separated by one degree of latitude and the distance between
them to be 66⅔ Arabic miles (131 km) and thus calculated the
Earth's circumference to be 24000 Arabic miles (47,000 km), a
value which differs from modern estimates by about 18.6%.

Another estimate given by al-Ma'mun's astronomers was 56⅔ Arabic
miles per degree, which corresponds to per degree and a
circumference of , very close to the currently modern values of per
degree and circumference, respectively.

Abū Rayhān
al-Bīrūnī (973-1048) solved a complex geodesic equation in order to accurately compute the
Earth's circumference, which was close
to modern values of the Earth's circumference. His estimate of for
the Earth radius was only less than the
modern value of . In contrast to his predecessors who measured the
Earth's circumference by sighting the Sun simultaneously from two
different locations, al-Biruni developed a new method of using
trigonometric calculations based on the
angle between a plain and mountain top which yielded more accurate
measurements of the Earth's circumference and made it possible for
it to be measured by a single person from a single location.

Many Muslim scholars declared a mutual agreement (Ijma) that celestial bodies are round, among them
Ibn Hazm (d. 1069), Ibn al-Jawzi (d. 1200), and Ibn Taymiya (d. 1328). Ibn Taymiya said,
"Celestial bodies are round—as it is the statement of astronomers
and mathematicians—it is likewise the statement of the scholars of
Islam". Qutb al-Din
al-Shirazi (d.1311) drew a planetary model which depicted the
celestial bodies in an epicyclic model. Abul-Hasan ibn al-Manaadi,
Abu Muhammad Ibn Hazm, and Abul-Faraj Ibn Al-Jawzi have said
that the Muslim scholars are in agreement that all celestial bodies
are round. Ibn Taymiyah also remarked that Allah has said, "And He
(Allah) it is Who created the night and the day, the sun and the
moon. They float, each in a Falak." Ibn
Abbas says, "A Falaka like that of a spinning wheel." The word
'Falak' (in the Arabic language)
means "that which is round."

The
Muslim scholars who held to the round earth theory used it in an
impeccably Islamic manner, to calculate the distance and direction
from any given point on the earth to Makkah. This determined the Qibla, or Muslim direction of prayer. Muslim
mathematicians developed spherical trigonometry which was used
in these calculations. Ibn Khaldun (d.
1406), in his Muqaddimah, also identified
the world as spherical. The later belief of Muslim scholars, like
Suyuti (d. 1505), that the earth is flat
represents a deviation from this earlier opinion.

Modern myth of the Flat Earth

During the 19th century, the Romantic
conception of a European "Dark Age" gave
much more prominence to the Flat Earth model than it ever possessed
historically. It is a modern misconception that the prevailing
cosmological view during the Middle Ages
saw the Earth as flat, instead of spherical. During the early Middle Ages,
many scholars maintained the spherical viewpoint first expressed by
the Ancient Greeks. By the 14th century, belief in a flat earth
among the educated was essentially dead. Flat-Earth models were in
fact held at earlier (pre-medieval) times, before the spherical
model became commonly accepted in Hellenistic astronomy..

In 1945 the Historical
Association listed "Columbus and the Flat Earth Conception"
second of twenty in its first-published pamphlet on common errors
in history.

Transvaal perspective

In 1898 during his solo circumnavigation of the world Joshua Slocum encountered such a group in
Durban. Three Boers, one of them a clergyman, presented Slocum with
a pamphlet in which they set out to prove that the world was flat.
President Kruger of the Transvaal Republic advanced the same view: "You don't mean
round the world, it is impossible! You mean
in the world. Impossible!"

Flat Earth Society

The last known group of Flat Earth proponents, the Flat Earth Society, kept the concept
alive and at one time claimed a few thousand followers. The last
president of the Society, Charles
K.Johnson, spent years
examining the studies of flat and round earth theories and proposed
evidence of a conspiracy against
flat-earth: "The idea of a spinning globe is only a conspiracy of
error that Moses, Columbus, and FDR all fought…" His article was
published in the magazine Science
Digest, 1980. It goes on to state, "If it is a sphere, the
surface of a large body of water must be curved. The Johnsons have
checked the surfaces of Lake Tahoe and the Salton Sea (a shallow
salt lake in southern California near the Mexican border) without
detecting any curvature."

The Society declined in the 1990s following a fire at its
headquarters in California and the death of Charles K. Johnson in
2001.

Other modern flat-earthers

William Carpenter (1830-1896) published "A hundred proofs the Earth
is not a Globe". For example, he argues that "there are rivers that
flow for hundreds of miles towards the level of the sea without
falling more than a few feet — notably, the Nile, which, in a
thousand miles, falls but a foot. A level expanse of this extent is
quite incompatible with the idea of the Earth's 'convexity'"; and
that an aeronaut at the highest possible altitude will see what
appears to be a concave surface "this being exactly what is to be
expected of a surface that is truly level, since it is the nature
of level surfaces to appear to rise to a level with the eye of the
observer".

English scientist Samuel Rowbotham
(1816-1885), writing under the pseudonym "Parallax," published
results of many experiments which tested the curvatures of water
over lakes. He also produced studies which purported to show the
effects of ships disappearing below the horizon can be explained by
the laws of perspective in relation to the human eye.

A BBC news website article from August 2008 showed there are still
people who firmly believe that the earth is flat, despite all the
evidence which points to it being spherical. In a 2009 BBC
interview, Mohammed Yusuf, leader of
the militant Islamic group Boko Haram, stated that the belief that the world is a sphere
is contrary to Islam and should be rejected, along with "Darwinism" and the theory that rain comes from water evaporated by the
sun.

Cultural references

The notion of a flat Earth continues to be referred to in a wide
range of contexts. Indirect references to the theory include the
widely used idiom "the four corners of the earth".

An early mention in literature was Ludvig
Holberg's comedy Erasmus Montanus (1723). Erasmus
Montanus meets considerable opposition when he claims the Earth is
round, since all the peasants hold it to be flat. He is not allowed
to marry his fiancée until he cries "The earth is flat as a
pancake". In Rudyard Kipling's
The Village that Voted the Earth was Flat, the
protagonists spread the rumor that a Parish Council meeting had
voted in favor of a flat Earth.

Fantasy fiction is particularly rich
in references to the flat Earth. In C.S.Lewis'
The Voyage of the
Dawn Treader the fictional world of Narnia is "round like a table" (i.e., flat),
not "round like a ball", and the characters sail toward the edge of
this world. Terry Pratchett's
Discworld novels (1983 onwards) are set on
a flat, disc-shaped world resting
on the backs of four huge elephants which are in turn standing on
the back of an enormous turtle. Many explorers died falling off the
edge trying to prove that it's not so.

The term 'flat earthers' is a recognizable slang, referent to
persons or organizations who cling to antiquarian beliefs which
have long since been disproven.

When Aquinas wrote his Summa, at the very beginning ( Summa Theologica Ia, q. 1, a. 1; see also
Summa Theologica IIa Iae, q. 54, a. 2), the
idea of a round earth was the example used when he wanted to show
that fields of science are distinguished by their methods rather
than their subject matter... "Sciences are distinguished by the
different methods they use. For the astronomer and the physicist
both may prove the same conclusion - that the earth, for instance,
is round: the astronomer proves it by means of mathematics, but the
physicist proves it by the nature of matter.History of Science: Shape of the Earth: Middle
Ages: Aquinas"

When Aquinas wrote his Summa, at the very beginning ( Summa Theologica Ia, q. 1, a. 1; see also
Summa Theologica IIa Iae, q. 54, a. 2), the
idea of a round earth was the example used when he wanted to show
that fields of science are distinguished by their methods rather
than their subject matter... "Sciences are distinguished by the
different methods they use. For the astronomer and the physicist
both may prove the same conclusion - that the earth, for instance,
is round: the astronomer proves it by means of mathematics, but the
physicist proves it by the nature of matter.History of Science: Shape of the Earth: Middle
Ages: Aquinas"